There are many different designs of baby buggies, but usually they consist of a frame having a seat or cot supported on the frame. It is recommended that newborn babies lie flat in a buggy. Therefore buggies for newborn babies have a cot or bassinet, having a flat bed on which to place the baby. The cot has upright sides to prevent the baby from falling out. Buggies having cots or bassinets are often referred to as prams. As a child grows older it is desirable for the child to be seated in an upright position. Therefore buggies are provided with seats, which usually include a backrest and seat cushion, supporting the child in an upright position. Often the inclination of the seat back can be changed, so that the child can recline in the buggy. Some buggies have means for interchangeably receiving a cot or an upright seat. These are known as travel system buggies.